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Aviation History
1985
1985 - 3144.PDF
-< airframe. Aerospatiale is studying a backup material to replace the ceramic » shingles should the idea prove unworkable. Essentially it is a metallic version of the multilayer material. The cooler upper surfaces of Hermes will be protected Orbiter-style by a flexible layer made up from low-density, glassfibre-like ceramic blankets. The spaceplane environmental control and life support system will supply cabin pressurisation, air, and water, as well as heating and cooling, and will involve air, water, and freon cooling loops, with radi ators located Orbiter-style inside the open cargo bay doors. The system must support 40 man-days in orbit, with an option to increase this to 90 man-days. The critical power-supply issue is the development of a motor working off liquid oxygen and liquid hydrogen, says Cnes. In addition, fuel-cell technology is not . currently available in Europe, which has no manned spaceflight experience. Cnes therefore plans to buy ten US-built fuel < cells for development and production of the two Hermes vehicles initially planned. Cnes expects Hermes' shape to change little over the next two years, during which 90 per cent of the design will be 4 completed. The present shape largely results from subsonic testing in the Onera windtunnel, as subsonic requirements I impose important constraints on the design. The aerodynamic team at present j comprises Dassault, Aerospatiale, Germany's DFVLR, and Belgium. To minimise Hermes design uncer- * tainties and risk, Dassault is proposing a halfway check using a 1 • 4-tonne, 1-scale j aerothermal demonstrator called Maia, to be launched by Ariane 4 for re-entry stud ies. In view of Europe's inexperience in both manned spaceflight and re-entry, Dassault feels that such a craft is neces- • sary to ensure the safe operation of Cnes has outlined likely recovery schemes should a Hermes mission be aborted before the spaceplane reaches orbit, including landing back at Kourou, recovery at sea, or landing at an emergency runway 26 FLIGHT INTERNATIONAL, 30 November 1985 Dassault proposed the shape which Cnes has adopted for Hermes, a highly swept delta with wingtip fins ronmental control and life support, power supply, and aerodynamics. Hermes re-entry conditions will be worse than those of the Shuttle Orbiter, says Cnes. Because the spaceplane is smaller, the aerothermal pressures will be higher. Baseline studies are being carried out by Dassault and SEP, with Aero spatiale responsible for work on backup materials. In the baseline thermal protec tion scheme the nose and leading edges are carbon-carbon components with an anti oxidant layer, either carbon or selesium oxide, deposited on the surface. These surfaces must withstand 1,400-1,600° C for 20min. This technology has been proven on the Orbiter, Cnes notes. The underside of the wing and fuselage will use tiles, but of a different design to those on the Orbiter, which continue to encounter operational problems, says Cnes. The baseline idea is to use "shingles"—a thin, black reinforced ceramic/carbon honeycomb composite layer beneath which is multilayer insulation—layers of a low-density ceramic material separated by thin sheets of metal to reflect the heat. Because this metal must withstand high temperatures, engine-type alloys are being investigated. The reuseable shingles will be fastened rather than bonded to the Hermes
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